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Error Identifier: isset.expr

Every error reported by PHPStan has an error identifier. Here’s a list of all error identifiers. In PHPStan Pro you can see the error identifier next to each error and filter errors by their identifiers.

Code example #

<?php declare(strict_types = 1);

function doFoo(int $value): void
{
	if (isset($value)) {
		// ...
	}
}

Why is it reported? #

The expression inside isset() is never null based on the types PHPStan has inferred, so the isset() check is unnecessary – it will always evaluate to true. The variable $value is typed as int, which cannot be null, so isset($value) serves no purpose.

The same applies to empty() checks and ?? (null coalescing) expressions when the left side is never null.

How to fix it #

Remove the unnecessary isset() check if the value is always defined and non-null:

-	if (isset($value)) {
+	if (true) { // or simply remove the condition
 		// ...
 	}

If the value should be nullable, update the type declaration:

-function doFoo(int $value): void
+function doFoo(?int $value): void
 {
 	if (isset($value)) {
 		// ...
 	}
 }

How to ignore this error #

You can use the identifier isset.expr to ignore this error using a comment:

// @phpstan-ignore isset.expr
codeThatProducesTheError();

You can also use only the identifier key to ignore all errors of the same type in your configuration file in the ignoreErrors parameter:

parameters:
	ignoreErrors:
		-
			identifier: isset.expr

Rules that report this error #

• PHPStan\Rules\Variables\EmptyRule [1]
• PHPStan\Rules\Variables\IssetRule [1]
• PHPStan\Rules\Variables\NullCoalesceRule [1]

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